@article{KubasCassanBeaulieuetal.2005, author = {Kubas, Daniel and Cassan, A. and Beaulieu, Jean-Philippe and Coutures, C. and Dominik, M. and Albrow, Michael D. and Brillant, Stephane and Caldwell, John A. R. and Dominis, Dijana and Donatowicz, J. and Fendt, Christian and Fouque, P. and Jorgensen, Uffe Grae and Greenhill, John and Hill, K. and Heinm{\"u}ller, Janine and Horne, Keith and Kane, Stephen R. and Marquette, Jean-Baptiste and Martin, Ralph and Menzies, J. W. and Pollard, K. R. and Sahu, K. C. and Vinter, C. and Wambsganss, Joachim and Watson, R. and Williams, A. and Thurl, C.}, title = {Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET observations}, issn = {0004-6361}, year = {2005}, abstract = {We analyze the photometric data obtained by PLANET and OGLE on the caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to the excellent photometric and spectroscopic coverage of the event, we are able to constrain the lens model up to the known ambiguity between close and wide binary lenses. The detection of annual parallax in combination with measurements of extended-source effects allows us to determine the mass, distance and velocity of the lens components for the competing models. While the model involving a close binary lens leads to a Bulge- Disc lens scenario with a lens mass of M = (0.51 ± 0.15) M-\⊙ and distance of D-L = (2.9 ± 0.4) kpc, the wide binary lens solution requires a rather implausible binary black-hole lens ( M \≳ 126 M-\⊙). Furthermore we compare current state-of-the-art numerical and empirical models for the surface brightness profile of the source, a G5III Bulge giant. We find that a linear limb-darkening model for the atmosphere of the source star is consistent with the data whereas a PHOENIX atmosphere model assuming LTE and with no free parameter does not match our observations}, language = {en} } @article{MortonsonSchechterWambsganss2005, author = {Mortonson, M. J. and Schechter, P. L. and Wambsganss, Joachim}, title = {Size is everything : universal features of quasar microlensing with extended sources}, issn = {0004-637X}, year = {2005}, abstract = {We examine the effect that the shape of the source brightness profile has on the magnitude fluctuations of images in quasar lens systems due to microlensing. We do this by convolving a variety of accretion disk models (including Gaussian disks, uniform disks, "cones," and a Shakura-Sunyaev thermal model) with two magnification maps in the source plane, one with convergence kappa = 0.4 and shear gamma = 0.4 (positive parity) and the other with kappa = gamma = 0.6 ( negative parity). By looking at magnification histograms of the convolutions and using chi(2) tests to determine the number of observations that would be necessary to distinguish histograms associated with different disk models, we find that, for circular disk models, the microlensing fluctuations are relatively insensitive to all properties of the models except the half-light radius of the disk. Shakura-Sunyaev models are sufficiently well constrained by observed quasar properties that we can estimate the half-light radius at optical wavelengths for a typical quasar. If Shakura-Sunyaev models are appropriate, the half-light radii are very much smaller than the Einstein rings of intervening stars, and the quasar can be reasonably taken to be a point source except in the immediate vicinity of caustic-crossing events}, language = {en} }